Row spacing and seeding rate effects in wheat and barley under a conventional fallow management system

Varying seed row spacing had no effect on the yield of spring wheat (Triticum aestivum L.) or barley (Hordeum vulgare L.) when grown under a conventional-tillage fallow-management system. Grain yields were improved with increased seeding rates by 14% in wheat and 32% in barley. The absence of a row-spacing-by-seeding-rate interaction suggests that adjustments in seeding rates are not required with changes in row spacing. The presence of surface residues and standing stubble cannot explain the lack of a row-spacing effect when using a zero-tillage stubble-cropping system, since similar results were obtained with a conventional-tillage fallow management system in this study.